This is book 5 of the "Nero Wolfe Continuation" series.

This note does not contain major spoilers for the book.

Wolfe and Archie dive into a case of industrial espionage involving a small plucky ad agency being relentlessly stolen from by a large established ad agency. The product appears to be a cherry cola, and one of the brands is using a name playing off "Cherokee" (and giving lots of profits to the tribes).

This one, as I vaguely recall, is rather clumsy.